"Today for the P55 launch we have two of Gigabyte's 11 P55 motherboards up for review. The GA-P55-UD6 is their high-end P55 motherboard with every feature known to man crammed onto an ATX motherboard. Ok, maybe not a every feature but close. The GA-P55M-UD4 is their high-end P55 mATX motherboard featuring the vast majority of the options on the GA-P55-UD6 albeit laid out on a compact mATX canvas. The only thing missing on the GA-P55M-UD4 is the TPM security module, the onboard LED debug reader, half(12) of the power phases, and a few expansion slots which might sound like a lot but in reality isn't nearly that much..."